Adjustable elastic scale drafting instrument



c. w. EWING 3,120,707

ADJUSTABLE ELASTIC SCALE DRAFTING INSTRUMENT Feb. 11, 1964 Filed March 21, 1961 Q INVENTOR. [2425/1/66 M [WM/G Arne/v5 f United States Patent 3,120,707 ADJUSTABLE ELASTIC SCALE DRAFTIVG INSTRUMENT Clarence W. Ewing, 107i) Hiilerest Drive, Harrisenbnrg, Va. Filed Mar. 21, 1961, Ser. No. 97,250 2 Claims. (Cl. 33137) This invention relates to an adjustable elastic scale drafting instrument and has for an object to provide a readily adjustable elastic scale drafting instrument particularly useful for drafting or plotting the contour of topographic maps, and for other suitable uses Where an elastic scale is desirable, particularly for the draftsman, civil engineer, architect, etc.

With the above and related objects in view, this invention consists in the details of construction and combination of parts, as will be more fully understood from the following description, when read in conjunction with the accompanying drawing in which:

FIG. 1 is a top plan view of the adjustable elastic scale drafting instrument of this invention.

FIG. 2 is an elevational view thereof.

FIG. 3 is a sectional view on line 3-3 of FIG. 2, showing the elastic band rotating mechanism.

FIG. 4 is a sectional view on line 44 of FIG. 2.

FIG. 5 is a sectional view on line 55 of FIG. 2.

There is shown at the adjustable elastic scale drafting instrument of this invention. This instrument comprises an elongate base bar 12 provided with a plurality of spaced-apart handle knobs 14, 16 and 18 suitably secured thereto for the convenience of the draftsman in handling and manipulating this instrument.

The elastic scale instrument includes a readily replaceable graduated rubber band 20, the elastic rubber band 29 being mounted on two spaced-apart rollers 22 and 24 appropriately mounted on the elongate base bar 12 as hereinafter described.

The inner surface 26 of the band 20 as mounted on the roller, is provided with suitable graduations 28. It will be understood that a series or plurality of different bands 26 may be provided, each band having a diiferent set of graduations suitable for the particular job for which it is intended. Any arbitrary graduations may be provided, according to the particular job desired. Obviously, with different graduations on different bands, a band appropriate to a particular proportion on a contour map may be selected for use on that particular map, and may be made to fit the particular map exactly because of the fact that the band 20 as mounted on the roller may be extended or permitted to contract by use of its mounting means. This mounting means is adjustable due to the fact that the roller 24 is journaled on the off-set end of a slide bar 36 which extends through a pair of spaced-apart pairs of bearing plates 32 and 34 suitably and permanently secured in appropriate spaced-apart relationship on the elongate base bar 12, as shown.

The bearing plates 32 include an upper plate 36 and a lower foot plate 33 secured at 40 to the base bar 12, the securing means, such as screws, also extending through vertical flange bars 42 providing a space through which the slide bar 34) slidably etxends. The bearing plates 34 also include an upper bearing plate 44 and a lower bearing foot plate 46 and similar flange bars 48 and 5t similarly secured by a screw or fastening means 52 extending therethrough.

The bearing plate 44 is provided with an upstanding ear 54 which is provided with a threaded aperture to receive one end 56 of a turnbuckle screw 58, the opposite end 60 being reversedly threaded to the end 56 and extending through a threaded ear 62 of a clamp bearing 64 provided with a thumb screw 66 for clamping the bearing 64 into locking engagement with the slide bar 36 so that when the thumb screw 66 is tightened down into contact with the slide bar 30, rotation of the turnbuckle screw 58 in one direction will move the slide bar 36 for a fine adjustment in one direction, while rotation in the other direction moves the slide bar 30 in the opposite direction.

When the thumb screw 66 is loosened sufiiciently to be out of contact with slide bar 30, the slide bar 30 may readily slide, under manual manipulation of the handle knob 70, for making a rough adjustment of the slide bar, and if this rough adjustment is sufiicient, a thumb set screw 68 threaded through upper bearing plate 36 may contact the slide bar 30 and lock it in position.

Obviously, both thumb set screws 66 and 68 must be loose, if the slide bar 30 is to be manipulated, and while thumb set screw 66 will prevent slide bar 30 from moving under manipulation of the handle knob 70, thumb set screw 66 alone will prevent movement of the slide bar 30 except against accidental rotation of the turnbuckle screw 58 and to prevent this, the other locking thumb set screw 68 Will also be utilized.

In order to bring the graduations 23 on the inner side 26 into proper alignment with the contour lines of the topographic map or whatever else is used, one of the rollers 22 or 24 should be readily controllable to rotate the band thereon, while the other roller rotates freely. In this case, it has been found convenient to make roller 22 controllable by having a bevel gear 72 fixed on one end thereof and meshed with a second bevel gear 74 on the end of a vertical shaft 76 controlled by a knurled handle 78 fixed on the end thereof. Shaft 76 extends through an overlying end 79 of a plate 86 suitably secured on one end of the base bar 12 by means of screws 82 extending through a suitable spacer tab 84 and through the bar 12 into a foot plate 86. The bottom of the foot plate 86 and the bottom of each of the bearing foot plates 38 and 46 are all in the same plane and provide supporting feet for the entire mechanism, and obviously, the bottom of the clamping mechanism 64 is slightly above the same plane. The roller 22 is journaled on a shaft 88 secured in a spacer tab 89 held in position by two of the screws 82 therethrough.

In operation, the draftsman manipulates the drafting instrument 16 by means of the knobs i4, 16 and 18, having the base bar 12 towards him and the slide bar and rotatable elastic band on the side away from him, so that the graduations 28 on the inner roller side of the band 26 are readable by him and brought into close juxta position to the map on which he is working.

The band can be stretched or permitted to contact by manipulating the slide bar 30 by means of the handle knob 70, after both thumb set screws 66 and 68 are loosened, and if satisfied with the rough adjustment, he may tighten the thumb set screw 68 or, if a fine adjustment is necessary, instead he tightens the thumb set screw 66 and then operates the turnbuckle screw 58 for fine adustment, and when the fine adjustment is secured, he then locks the slide bar 3'9 against accidental movement by tightening the thumb set screw 68.

Either before or after adjusting the slide bar 30, as necessary, he can position the graduations 28 appropriately by merely rotating the rotary control handle 78 through which, through the bevel gears 74 and 72 will rotate the roller 22 and its companion roller 24, the companion roller 24 being journaled on a shaft 96 in the offset end of the slide bar 30.

Obviously, both rollers 22 and 24 may be provided with suitable flanges 92 for keeping the band 20 in proper position thereon. The draftsman holds the entire mechanism by placing one hand over one or more of the handle knobs 14, 16 and 18 and uses his other hand to adjust the slide bar 30 and the position of the rubber band 20 by rotating the roller control knob 73 as desired. Then, he reads off the distances between the contour lines as desired on the graduations 28 and readily proportions the same in making his contour plotting, and thus reduces the time necessary in contour plotting a considerable amount, speeding up his work and making him more eflicient.

Although this invention has been described in considerable detail, such description is intended as being illustrative rather than limiting, since the invention may be variously embodied, and the scope of the invention is to be determined as claimed.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

1. An adjustable elastic scale drafting instrument comprising an elonagte base bar, a pair of rollers, means for mounting said rollers on said elongate base bar in adjustably spaced-apart relationship, a graduated elastic endless band mounted on said rollers, manual control means associated with one of said rollers for rotating said one roller to thereby rotate said graduated elastic band thereover, additional manual control means associated with one of said rollers for adjusting the position of said one roller on said base bar to thereby adjust the length of said elastic band between said rollers, said additional manual control means comprising a slide bar on which said one roller is rotatably mounted, and bearing means fixed on and extending to one side of said elongate base bar through which said slide bar slidably extends, and rough adjustment means and fine adjustment means mounted on said slide bar for sliding said bar through said bearing means to a desired position and for holding said slide bar in the desired position, said rough adjustment means comprising a handle knob on said slide bar for manually sliding said slide bar through said bearing means for rough adjustment of said slide bar, said fine adjustment means comprising a turnbuckle screw threaded at both ends in separated female threads, means basing one of said female threads on said elongate bar, means basing the other of said female threads on said slide bar, one of said basing means being fixedly mounted on said elongate base bar, the other of said basing means being releasably mounted, and thumb set screw means for locking said slide bar in adjusted position.

2. The drafting instrument of claim 1, said roller mounting means and said bearing means each including fiat foot plates having their bottom surfaces in a common plane below the plane of all other parts of said instrument, said foot plates providing supporting feet for said instrument.

References Cited in the file of this patent UNITED STATES PATENTS 120,621 Chassaing Nov. 7, 1871 1,445,526 McMorris Feb. 13, 1923 2,484,151 Brownell M Oct. 11, 1949 FOREIGN PATENTS 146,585 Great Britain July 5, 1920 

1. AN ADJUSTABLE ELASTIC SCALE DRAFTING INSTRUMENT COMPRISING AN ELONGATE BASE BAR, A PAIR OF ROLLERS, MEANS FOR MOUNTING SAID ROLLERS ON SAID ELONGATE BASE BAR IN ADJUSTABLY SPACED-APART RELATIONSHIP, A GRADUATED ELASTIC ENDLESS BAND MOUNTED ON SAID ROLLERS, MANUAL CONTROL MEANS ASSOCIATED WITH ONE OF SAID ROLLERS FOR ROTATING SAID ONE ROLLER TO THEREBY ROTATE SAID GRADUATED ELASTIC BAND THEREOVER, ADDITIONAL MANUAL CONTROL MEANS ASSOCIATED WITH ONE OF SAID ROLLERS FOR ADJUSTING THE POSITION OF SAID ONE ROLLER ON SAID BASE BAR TO THEREBY ADJUST THE LENGTH OF SAID ELASTIC BAND BETWEEN SAID ROLLERS, SAID ADDITIONAL MANUAL CONTROL MEANS COMPRISING A SLIDE BAR ON WHICH SAID ONE ROLLER IS ROTATABLY MOUNTED, AND BEARING MEANS FIXED ON AND EXTENDING TO ONE SIDE OF SAID ELONGATE BASE BAR THROUGH WHICH SAID SLIDE BAR SLIDABLY EXTENDS, AND ROUGH ADJUSTMENT MEANS AND FINE ADJUSTMENT MEANS MOUNTED ON SAID SLIDE BAR FOR SLIDING SAID BAR THROUGH SAID BEARING MEANS TO A DESIRED POSITION AND FOR HOLDING SAID SLIDE BAR IN THE DESIRED POSITION, SAID ROUGH ADJUSTMENT MEANS COMPRISING A HANDLE KNOB ON SAID SLIDE BAR FOR MANUALLY SLIDING SAID SLIDE BAR THROUGH SAID BEARING MEANS FOR ROUGH ADJUSTMENT OF SAID SLIDE BAR, SAID FINE ADJUSTMENT MEANS COMPRISING A TURNBUCKLE SCREW THREADED AT BOTH ENDS IN SEPARATED FEMALE THREADS, MEANS BASING ONE OF SAID FEMALE THREADS ON SAID ELONGATE BAR, MEANS BASING THE OTHER OF SAID FEMALE THREADS ON SAID SLIDE BAR, ONE OF SAID BASING MEANS BEING FIXEDLY MOUNTED ON SAID ELONGATE BASE BAR, THE OTHER OF SAID BASING MEANS BEING RELEASABLY MOUNTED, AND THUMB SET SCREW MEANS FOR LOCKING SAID SLIDE BAR IN ADJUSTED POSITION. 